1. Field of Invention
This invention relates to speech recognition systems.
2. Description of Related Art
As the amount of information communicated within communication systems continues to increase, there is an increase in the use of communications devices. On mobile communications devices, space limitation is a significant problem as the size of the mobile devices that are manufactured continues to decrease. For example, the space on a small mobile device can limit the mobile device to having a limited resolution display, limited pen or mouse input modalities, a limited-sized keyboard and/or no keyboard at all. Each mobile communication device can have various modalities that allow an end user to input data into or operate the mobile device.
The solve this problem, input devices on a mobile device can be given multi-function capability. For example, multi-function keys are currently used to reduce the number of keys required on a mobile device. However, multi-function keyboards are difficult to use and tend to result in numerous errors during operation. For example, some systems used in web-enabled telephones attempt to predict complete words as the words are being entered using keys on the keyboard. However, these predictive text entry systems often completely mis-identify words and do not easily adapt to words in a different language. If no keyboard is used on the mobile device, a mouse or pen can be used. However, using the mouse or pen on a small mobile device to communicate a large amount of data can be awkward and inconvenient.
Moreover, with a limited number of input devices that correspond to various modalities of the mobile device, the implementation of a particular service, i.e., a word recognition service, can become more difficult. In order to increase word recognition capability, some mobile devices have included a larger keyboard. For example, some web-enabled telephones are equipped with a flip-up case that provides a larger touch sensitive screen for input functions. However, these screens are expensive and increase the likelihood of damage to the device due to the complexity of the screens. Furthermore, because these screens have increased power requirements, they prevent a reduction in the size of a portable battery used with the mobile device.
Although some mobile devices, such as personal digital assistants (PDA) include handwriting recognition software, the software suffers from inaccurate word recognition, and the user is required to write on the screen using a specialized set of characters or in a manner that is easily recognizable by the program.
In order to solve the above-mentioned problems, automatic speech recognition (ASR) systems have been used in mobile devices as an improved method of communicating information using the mobile device. However, the ASR systems for mobile devices must be able to adapt to various users, as well as the different characteristics associated with various devices. For example, each mobile device is likely to use a microphone having different response characteristics. Likewise, various background noise environments must be taken into consideration because mobile devices may move throughout a constantly changing background environment as the user transcends from one area to another.
Accordingly, there exists a need to improve the performance of ASR services by not making mandatory various complex or supervisory steps that the end user must perform to provide data to the ASR system service provider. Although end user input could always be used as part of the ASR system, by not making these steps mandatory, the efficiency and accuracy of the ASR system can be significantly improved.